Manufacture of carbon electrodes.



S. E. SIEURIN.

MANUFACTURE OF CARBON ELECTRODES.

APPLICATION FILED OCT. 16. 1911.

1,282,475. Patented Oct 22,1918.

x/vv /vra/ 6 47 WW W sm EKIL SIEURIN, 0F EMANKS, SWEDEN.

MANUFACTURE OF CARBON ELECTRODES.

Specification of Letters Patent.

Patented Oct. 22, 1918.

Application filed October 16, 1917. Serial No. 196,868.

To all whom it may concern:

Be it known that I, SVEN EMIL SmUnIN, a subject of the King of Sweden, residing at Hoganas, Sweden, have invented new and useful Improvements in the Manufacture of Carbon Electrodes, of which the following is a specification.

In the manufacture of carbon electrodes a mixture of retort graphite and anthracite, calcined in a retort furnace, hitherto has been used. Electrodes manufactured from anthracite alone are not of a good quality because the mass is not sufiiciently plastic for the necessary pressin and moreover the conductivity of the nished electrodes is low. It has been found that 00d electrodes cannot be manufactured if t e quantity of retort graphite contained in them is under about 30%.

Since long ago it has been known, that material rich in carbon after long heating at a very high temperature in an electric furnace is transformed into graphite at an intermittent workin'g. Graphite, produced in this manner, of course is suitable for the manufacture of electrodes, but on account of the large consumption of current it becomes too costly for use in place of retort carbon in the usual furnace electrodes.

According to the present method the carbonaceous raw material (anthracite, coke etc.) is also heated in an electric resistance furnace, but the temperature used is not so high that any formation of graphite, worthy of consideration, takes place. By such a heating or calcination, which takes place at a temperature higher than that obtainable by an external heating in a retort, the carbonaceous material is transformed into a product of high electric conductivity and suitable for use as a substitute for'retort graphite. Experiments have proven that about 1000 kilowatt hours per ton calcined material are suflicient for the purpose, whereas at the transforming of carbonaceous material into graphite according to the method of Acheson, usually 3000 kilowatt hours per ton graphite are required. Experiments have also shown that the carbon .ture but not exceeding calcined according to the present method without difficulty can be formed and pressed and that the electrodes manufactured in this manner possess good conductivity. In the practice such electrodes have been found to be better than the usual electrodes of retort graphite, especially as to. their conductivity and resistance against burning.

The method is suitably carried out in an electric shaft furnace. On the annexed drawing such a furnace is illustrated in vertical section in Figure 1 and in horizontal section in Fig. 2.

a is the shaft of any suitable fire proof material, 6 is the upper electrode and 0 feed openings for the raw material. At the lower end of the furnace a bottom electrode at is placed, with a channel 6, communicating with an opening 7, through which the calcinated material is removed. This arrang'ement is found very suitable, although other arrangements may be used. For example, the channel 6 may pass on the side of the bottom electrode or, if several bottom electrodes are used, the channel passes between them. The furnace works as a resistance furnace in which the carbonaceous material itself forms the resistance against the current. The electrodes are as usually manufactured by crushing the material (the anthracite or coke) thus heated in the electric furnace, whereupon they are mixed with coal tar and other suitable binding materials to form a plastic mass, which mass is pressed into any suitable form by hydraulic presses. The electrodes thus produced are placed in furnaces, surrounded by carbon powder and then heated to 1300 to 1400 centigrade, whereby the tar and the other volatilematerials are expelled and the electrodes are ready for use.

Having now particularly described the nature of my invention and the manner of its operation, what I claim is:

1. An improved method of manufacture of carbon electrodes by heating materials richin carbon, as anthracite and coke, in an electrlc reslstance furnace near to the temperathat, at which graphite is formed, mixing the crushed ma- In testimony whereof I have signed my terial with binding materials, as coal tar, name to this specification in the presence of heating and pre ing into a sultable form. two subscribing witneses.

2. An electrode for electric furnaces con- SVEN EMIL SIEURIN. 5 sisting of carbon, heated in an electric re- Witnesses:

sistance furnace near to the temperature at B. BOi'GUAN,

which it is transformed to graphite. GUSTAFUND J OHANSSEN. 

